Grating for bridge floors and the like



April 3, 1956 G. G. GREuLlcH 2,740,335

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Aprilk 3, 1956 G. G. GREuLlcH 2,740,335

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ilnited States Patent O GRATING FOR BRIDGE FLOORS AND THE LIKE Gerald G.Greulicll, Pittsburgh, Pa.

Application June 27, 1951, Serial No. 233,732

3 Claims. (Cl. 94-30) This invention relates to open gratings that areused as floors or decks for bridges or airplane runways and the like, oras traffic supporting covers for subways, ditches or vaults.

Gratings of this character have been formed from bars crossing oneanother at right angles to form rectangular openings. Such gratings,with bars at right angles to the direction of traiiic, have been moreeicient in pre venting forward skidding or sliding of vehicles andsomewhat less eiiicient in preventing sidewise skidding than gratings inwhich the cross members are replaced by diagonal members that formtriangular openings having their bases relatively long and parallel tothe direction of traic. To overcome the poor resistance of gratings withrectangular openings to lateral or diagonal skidding, a number ofexpedients have been tried, such as placing the tops of the grating barsat different levels or notching their upper surfaces to produceserrations. I have found that when the long sides of a grating openingare parallel to the sides of a vehicles tires lateral skidding isgreatly reduced. This is because the tires can project down into theopening farther than when the short sides of an opening are parallel tothe tire sides. Since a tire has to rise up out of a grating openingbefore it can start to skid sidewise, an easy way to increase theanti-skidding characteristics of grating would appear to be to make theopenings square and larger. However, such an increase in size produces arough and bumpy ride over the grating. A smooth ride can be produced byusing triangular openings, because they have relatively long sideswithout excessive open areas. On the other hand, if the grating is ofthe type provided with triangular openings having their bases parallelonly to the direction of traic and without any cross bars at rightangles to the direction of tratic, forward skidding is increased and avery annoying and at times unsafe front wheel wobble is produced.

It is among the objects of this invention to provide an open gratingwhich reduces skidding of vehicles in any direction over it, which doesnot produce a bumpy ride nor wobbling of the front wheels of vehicles,which is stronger than previous gratings of comparable weights, whichcan be used with wider spans, which is formed with a minimum of welds,which can be used equally well with the longitudinal members parallel ortransverse to the direction of traflic, which does not require bottombracing of the beams, and which can be formed from prefabricated slabsthat are connected side by side in adjustable relation.

In accordance with this invention, a plurality of parallel metallongitudinal members are held in predetermined spaced relation invertical notches in parallel cross members, with the tops of all of themembers lying in substantially the same plane. The cross members arepreferably disposed substantially the same distance apart as thelongitudinal members to form therewith a plurality of substantiallysquare openings of relatively large size, but the openings can be oblongif desired. Extend- ICE ing across each of these openings is a diagonalmember, which is secured to the longitudinal and cross members at itsopposite ends. The diagonal members are arranged to form a repetitivesquare or parallelogram pattern superimposed on successive groups offour adjacent square or oblong openings, thus forming an arrangement oftriangular openings with their bases extending in four directions. Thecross members extend through trans verse openings in at least some ofthe longitudinal members. These openings are of such shape as to providethe maximum amount of material between adjacent openings in the samemember. The openings require the cross members to be inclined when theyare inserted in the openings and then rotated on a longitudinal axisinto upright position. It is preferred to form the diagonal membersbetween each pair of longitudinal members from a metal bar extendinglengthwise of the latter and reversely bent to extend back and forthbetween them. The notches in the cross members are wide enough toreceive the bars where they intersect the cross members, and welds aremade at the notches to join all of the members together and to the bars.The bars are so arranged that their diagonal portions on opposite sidesof a longi tudinal member radiate therefrom in four directions at theintersections of that member with alternate cross members. Preferably,the upper portions of the notches are upward to provide inclinedweld-receiving surfaces, and the tops of the diagonal bars at theintersections are provided with shallow notches which also receive thewelds. The grating is formed in slabs of convenient size for handling,and the cross members preferably project beyond the outermostlongitudinal members of each slab for connection to the slabs onopposite sides of it.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which Fig. 1 is a somewhat diagrammatic planView of a complete grating slab with portions of like slabs connected toit; Fig. 2 is an enlarged fragmentary plan view of one of the slabs;Fig. 3 is a vertical section taken on the line III-III of Fig. 2; Fig. 4is a vertical section taken on the line IV-IV of Fig. 2; Fig. 5 is afragmentary side view of the cross bar shown in Fig. 3; Fig. 6 is a sideview of the cross bar shown in Fig. 4; Fig. 7 is a longitudinal verticalsection taken on the line VII-VII of Fig. 2; and Fig. 8 is a fragmentaryperspective view showing the intersections of two of the diagonal barswith a cross bar beside a longitudinal member before welding.

Referring to the drawings, each grating slab is formed from a pluralityof parallel longitudinal metal members A and B of any desired length,alternating parallel cross bars C and D and zigzag bars E extendinglengthwise between the longitudinal members. The longitudinal memberspreferably are of two types alternating with each other. One type is arelatively heavy beam A which has flanges 6 extending along its loweredge to rest on the girders 7 or the like that support the grating. Eachbeam as a Wide web 8 terminating at its upper end in a thick head 9. Theother type of longitudinal member B is a narrow fiat bar which isdisposed on edge midway between the heads of each pair of beams. Thenumber of beams A and middle bars B in each slab depends upon the widthof slab desired. For very light loads, one heavy beam A may bealternated with two or three bars B. Also, it is optional whether bothof the outermost longitudinal members of a slab are beams, both middlebars or a beam at one side and a middle bar at the other side. In anyevent, the cross bars C and D preferably project a short distance beyondthe outermost longitudinal members of thepslab. The intersecting crossbars and longitudinal members provide the slab with a large number ofrectangular openings. Most suitably the cross members are spacedsubstantially the same distance apart as the longitudinal members toform substantially square openings, preferably about three or fourinches square, which is larger than is feasible for conventionalgratings.

The middle bars B are supported by cross bars C and D, the upperportions of which are provided with vertical notches 12, through whichthe middle bars extend. These notches are of such depth that the tops ofthe middle bars and the cross bars all lie in the same plane. The depth(width) of the cross bars is considerably greater than that of themiddle bars, but considerably less than that of the beams. Consequently,the beams have to be provided with transverse openings 13, through whichthe cross members can extend. The upper portions of the cross bars areprovided with additional notches 14 for receiving the portions of thebeams above openings 13, such portions being formed chiefly from theheads 9 of the beams, so that the tops of the beams will lie in the sameplane as the tops of the bars.

The beam openings 13 through which the cross bars extend have a specialshape which, along with the positions of the openings, forms part ofthis invention. Each opening or slot (Fig. 7) extends substantiallyequal distances from opposite sides of the cross bar that extendsthrough it, the combined distance being great enough to permit the crossbar to be inserted in the slot when tilted laterally at quite an angle.One half of the slot has a horizontal bottom wall 16 on which the crossbar rests. It also has a vertical wall 17 engaged by one side of thelower portion of the bar. The other half of the slot has a horizontaltop wall 18 substantially in engagement with the bottom of the cross barnotch 14 that receives the head of the beam, and it also has a verticalwall 19 engaging a portion of the side of the cross bar opposite to thelower vertical wall 17. The top wall 21 of the lower half of the slot isinclined downward from the lower end of upper vertical wall 19, and thebottom wall 22 of the upper half of the slot is inclined upward from theupper end of lower vertical wall 17. The two inclined walls 21 and 22are disposed in substantially parallel planes which are slightly fartherapart than the thickness of the cross bar. The outer ends of the twoinclined walls are connected to the adjacent horizontal walls of theslot by short end walls.

After the cross bar has been laid on its side in an inclined positionand inserted in the slot, the upper edge of the bar can be swung upwardas its lower edge is swung in toward the lower vertical wall 17 of theslot. The notch 14 in the upper portion of the cross bar will permit itto straddle the head of the beam as the bar is swung into uprightposition. The lower portion of the cross bar then can be welded to thebeam beside the lower vertical wall of the slot, although it is notnecessary to so weld every bar to every beam. The shape and inclinationof beam slots 13 is such that a maximum of solid metal is providedbetween the closest points of adjacent slots for a given depth of crossbar, because those points are spaced diagonally from each other. Also,by having only half of each slot directly below the beam head, and theother half of the slot at a lower level, considerably more support isgiven to the beam head. That is, with only half of the slot directlybelow the beam head, there is a considerable body of supporting metalbetween the beam head and the lower halt of the slot.

Extending lengthwise of the slab between each pair of longitudinalmembers is a continuous zigzag bar E that most suitably is the samewidth and thickness as middle bars B. Each E bar is reversely bent atuniformly spaced points to provide it with diagonal portions 24 thatextend back and forth between the adjoining beam and middle bar,diagonally across a series of the rectangular openings in the gratingsto divide each one into two triangular openings. At each bend in the barits diagonal portions are connected by a short portion that is parallelto and engages the adjoining longitudinal member at an intersection witha cross bar. It is another feature of this invention that the cross barnotches, through which the diagonal bars extend, are the same notchesthat receive the beams and middle bars. For this purpose theseparticular cross bar notches, which are staggered lengthwise of theslab, are made wide enough to also accommodate the E bars. The tops ofthe diagonal bars lie in the same horizontal plane as the rest of thebars. It will be seen that the directions of the diagonal portions ofeach E bar are reversed relative to the E bar on its opposite sides, sothat each intersection of the E bars with the cross bars there are fourdiagonal members which radiate in four directions from the intersection.It also will be seen that the diagonal members form squares around thealternate cross bar notches which they do not extend through.

A still further feature of this invention is that all of the bars andthe beams are welded together at the notches in the cross bars. Toprovide adequate surface area for butt welding, the upper portions ofthe notches are flared to provide inclined surfaces that form taperedpockets.

beside the members extending through the notches. Welding material 26 isdeposited in these pockets to weld the different members together. Byproviding each diagonal bar, where it lits in the notches, withdownwardly tapered shallow notches 27 (Fig. 8), the welding material canextend across the notches in the E bars and unite with the adjoiningmiddle bar or beam, as the case may be. Consequently, only two welds ateach intersection of the diagonal bars with the cross bar welds fourmembers together and those welds can be made from the top. These weldsalso help hold the cross bars upright in beam slots 13, by helping toprevent the bars from pivoting on the lower ends of the upper verticalwalls 19. Lower vertical walls 17 of the slots prevent the bottoms ofthe cross bars from moving in the opposite direction.

It is preferred to taper the upper portion of each beam headtransversely so that its upper surface will be no wider than thedifferent bars. v This improves the appearance of the grating from aboveand also reduces the width of the beam surface on which rain and ice canaccumulate.

For connecting these grating slabs side by side, the ends of the crossbars projecting from one side of each slab are bent laterally, as at 28,to oiset them the thickness of the bars. They then will overlap thestraight projecting ends of the cross bars of the next slab. Thisoverlapping permits the two slabs to be moved toward or away from eachother within limits, and then the overlapping cross bar ends can easilybe welded together by welding the end surfaces of some of the bars tothe sides ofthe overlapping bars. One end of each slab may be providedwith a transverse trim bar 29 welded to the projecting ends of thelongitudinal members and diagonale. When the slabs are laid, theprojecting members at the end of the next slab are welded to this trimbar.

lf desired, cross bars C and D can be provided along their neutral axeswith holes 31, through which reinforcing rods 32 can be inserted in caseit is desired to fill the upper portion of the grating with concrete. Insuch a case supporting pans 33 (Fig. 3) are mounted on ribs 34 extendingalong opposite sides of the beams a short distance below the cross bars.The spaces .between these pans and the top of the slab then can befilled with concrete.

This design of grating, with triangular openings throughout, permitsgreater space between cross bars C and D than with conventional designs,because the zigzag bars E separate each rectangular space into twotriangles, each ot which necessarily has no more than half the area ofthe rectangular space. This greater spacing of the cross bars allowsdeeper cross bars to be used without sacricing horizontal shear strengthin the beams A, since the wider spacing of the cross bars means that agreater amount of metal can be left between adjacent slots 13 throughany beam. Because deep cross bars can be used,

any need for conventional bottom bracing of the beams is eliminated andits weight and cost thereby saved. Also, when it is realized that thesection modulus of the cross bars goes up as the square of their depth,it is apparent that any increase in depth effects a much greaterincrease in transverse strength. This increase in transverse strengthprovides a much wider load distribution so that more beams A areeffective in carrying the load. Therefore, the individual beams arerequired to carry less load per unit, andthe length of'spans (thedistance between girders 7) over which the grating is used may beincreased appreciably without a comparable increase in weight of metalrequired in the beams.

The diagonal bars E carry their full complement of ange compressionstress in proportion to the cosine of the angle with the beam head 9.They also make the middle bars B effective in full cross section assupplemental area to the beam head. These bars form, in effect, a Y

laterally extending trussed ange system on each side of the beam head.It is thus seen that the diagonal bars perform the dual function ofbridging the space between beam heads and of helping the beams A inresisting bending moment.

One of the reasons for the economy of this grating is that severalelements are joined together by means of a single weld. Less than halfas many welds are required as are used in conventional welded gratingnow in wide use having a comparable area or size and number of openingsin the upper or supporting surface. By making the diagonal barscontinuous, a much smaller weld is required to retain them in positionand to function structurally than would be the case if they were shortindividual pieces. Fewer and smaller welds result in less warpage andtwist in the finished product, due to proportionately less shrinkageduring the cooling of the weld metal. This not only eliminates much ofthe cost of subsequent straightening and alignment, but it provideseconomically a better appearing and more acceptable product.

Economy inherent in my invention lies further in the fact that the slabsare universal in application. That is, due to the pattern formed by themembers in the grating surface, the slabs can be laid with the beamseither parallel or transverse to the direction of traic movement withoutaltering the appearance or surface characteristics ofthe grating.

According to the provisions of the patent statutes, I have explained theprinciple of my invention and have illustrated and described what I nowconsider to represent its best embodiment. However, I desire to have itunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically illustrated anddescribed.

l claim:

1. An open grating for bridge floors and the like, comprising aplurality of parallel longitudinal metal members, a plurality of spacedparallel metal cross members disposed on edge and having their upperportions provided with vertical notches receiving portions of saidlongitudinal members to hold the latter in predetermined spaced relationto form rectangular openings the upper portions of said notches beingwider than their lower portions, a metal bar extending lengthwisebetween each pair of longitudinal members and reversely bent to extendback and forth between them diagonally across each of said openings, thenotches in said cross members where those members are intersected bysaid bars being wider than the longitudinal members and each of thosenotches receiving two of the bars separated by the longitudinal memberin the same notch, whereby the diagonal portions of bars on oppositesides of a longitudinal member radiate therefrom in four directions atthe intersections of the bars with cross members, the bars beingprovided with shallow notches where they intersect the cross members,and a pair of welds at the top of the grating at each of saidintersections joining the longitudinal member to the adjoining bars andcross member, each of said welds filling one of said shallow notches.

2. An open grating for bridge floors and the like, comprising aplurality of spaced parallel metal beams disposed on edge and adapted torest on suitable supports, each of said beams being provided atlongitudinally spaced points with transverse slots, a plurality ofparallel cross bars disposed on edge and extending through said slots,the upper portions of the bars being provided with vertical notchesreceiving the portions of the beams above said slots, each of the slotshaving portions extending from opposite sides of the cross bar therein,one of said slot portions having a horizontal bottom wall on which thecross bar rests and a vertical wall engaging one side of the bar, theother portion of the slot having a vertical wall engaging the other sideof the bar above said one portion of the slot and also having ahorizontal top wall substantially in engagement with the bottom of thecross bar notch, the top wall of said one portion of the slot beinginclined downward from the lower end of said last-mentioned verticalwall, the bottom wall of the other portion of the slot being inclinedupward from the upper end of said lirst-mentioned vertical wall, saidinclined walls being disposed in substantially parallel planes slightlyfarther apart than the thickness of the cross bar to require the crossbar to be inclined when inserted in the slot and then rotated on alongitudinal axis into upright position against said vertical walls ofthe slot, and welds at said notches joining the bars to the beams.

3. An open grating for bridge tloors and the like, cornprising aplurality of parallel longitudinal metal members, a plurality of spacedparallel metal cross members disposed on edge and having their upperportions provided with vertical notches receiving portions of saidlongitudinal members to hold the latter in predetermined spaced relationto form rectangular openings, a metal bar extending lengthwise betweeneach pair of longitudinal members and reversely bent to extend back andforth between them diagonally across each of said openings, the notchesin said cross members where those members are intersected by said barsbeing wider than the longitudinal members of each of those notchesreceiving two-of the bars separated by the longitudinal member in thesame notch, whereby the diagonal portions of bars on opposite sides of alongitudinal member radiate therefrom in four directions at eachbar-receiving notch to form eight angles, and welding metal deposited ontop of each bar where it intersects a cross member and joined to thatmember at one side of the bar and to the longitudinal member at theopposite side of the bar.

References Cited in the file of this patent UNITED STATES PATENTS1,264,758 Berson Apr. 30, 1918 1,612,236 Thomson Dec. 28, 1926 2,128,753Liehard l Aug. 30, 1938 2,190,215 Nagin Feb. 13, 1940 2,275,104 GreulichMar. 3, 1942 2,425,054 Tarof Aug. 5, 1947 2,645,985 Beebe July 21, 1953

